Polyelectrolytes have proven their advantages as draw solutes in forward osmosis process in terms of high water flux, minimum reverse flux, and ease of recovery. In this work, the concept of a polyelectrolyte-promoted forward osmosis-membrane distillation (FO-MD) hybrid system was demonstrated and applied to recycle the wastewater containing an acid dye. A poly(acrylic acid) sodium (PAA-Na) salt was used as the draw solute of the FO to dehydrate the wastewater, while the MD was employed to reconcentrate the PAA-Na draw solution. With the integration of these two processes, a continuous wastewater treatment process was established. To optimize the FO-MD hybrid process, the effects of PAA-Na concentration, experimental duration, and temperature were investigated. Almost a complete rejection of PAA-Na solute was observed by both FO and MD membranes. Under the conditions of 0.48 g mL(-1) PAA-Na and 66 °C, the wastewater was most efficiently dehydrated yet with a stabilized PAA-Na concentration around 0.48 g mL(-1). The practicality of PAA-Na-promoted FO-MD hybrid technology demonstrates not only its suitability in wastewater reclamation, but also its potential in other membrane-based separations, such as protein or pharmaceutical product enrichment. This study may provide the insights of exploring novel draw solutes and their applications in FO related processes.
Fueled by non-linear growths in world population and water & energy consumption, global water and energy demands have risen exponentially in tandem with exacerbated environmental issues, necessitating the exploration of alternative clean water and renewable energy resources. By integrating pressure retarded osmosis (PRO) and membrane distillation (MD), this study has demonstrated an advanced PRO−MD hybrid process for sustainable generation of osmotic power and clean water from either freshwater or real wastewater. The proposed hybrid system exhibits unique advantages of high water recovery rate, huge osmotic power generation, well controlled membrane fouling, and minimal environmental impacts. We believe this work would provide insightful guidelines for the exploration of alternative green technologies for renewable osmotic energy and clean water production. further reduced by applying a heat exchanger in the hybrid system and using low-grade heat or 34 solar energy to heat up the feed solution. The newly developed PRO−MD hybrid process would 35 provide insightful guidelines for the exploration of alternative green technologies for renewable 36 osmotic energy and clean water production. 37
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